<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>canvas</title>
  <style>
    canvas{
      border: 1px solid black;
      background-color: antiquewhite;
    }
  </style>
</head>
<body>
  <canvas id="canvas" width="640" height="360"></canvas>
  <script>
    let cvs = document.getElementById('canvas')
    let ctx = cvs.getContext('2d')
    ctx.fillStyle ='red'
    ctx.fillRect(50,100,200,130)
  </script>
</body>
</html>